Vascular Plants of North Carolina
Account for Kidneyleaf Rosinweed - Silphium compositum   Michaux
Members of Asteraceae:
Members of Silphium with account distribution info or public map:
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Section 6 » Order Asterales » Family Asteraceae
AuthorMichaux
DistributionMore-or-less throughout the state, but with some gaps, notably the northeastern Outer Coastal Plain and the northern Mountains.

VA to TN, south to FL and AL.
AbundanceGenerally common in the Piedmont and most of the Coastal Plain, but very rare to absent in the far eastern and northeastern Coastal Plain. Fairly common in the southern half of the Mountains, and rare to absent in the northern counties.
HabitatDry to xeric soils of oak-hickory woodlands, glades and barrens, rocky slopes, Longleaf Pine-Wiregrass communities, savannas, sandhills, clearings, and roadsides.
PhenologyFlowering and fruiting late May-September.
IdentificationThe Silphium compositum complex consists of 3 varieties plus S. reniforme, according to Weakley (2018); 2 varieties occur in NC. The growth form of all is very distinctive: a basal rosette of very large (a foot long and 8 inches to a foot wide), stalked, palmately-lobed (except in S. reniforme) basal leaves that lie near the ground, with a single stem 5-7 feet tall and a widely-branched, open inflorescence of relatively small heads of sunflower-like flowers. As in other rosinweeds, the heads are yellow and the involucral bracts are thick-textured and rounded. Var. venosum differs in its broader involucres (1.5-3 cm wide vs. 1-1.5 cm) and longer seeds (8-14 mm long vs. 6-9 mm). S. reniforme differs in having unlobed leaves, or with a single lobe on each side. Kidneyleaf Rosinweed is a familiar and spectacular sight along many wooded margins and clearings, especially with stems often over head-height.
Taxonomic CommentsSome authors, such as FNA, do not recognize any varieties within S. compositum.

Other Common Name(s)Composite-leaf Rosinweed
State RankS5
Global RankG5
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